Breaking the rules: modifications of sexual reproduction pathways in vertebrates.

有性生殖在大多数真核生物中普遍存在，包括减数分裂和重组、配子减少、受精、核受精和新有机体的发育。打破这一规则，脊椎动物的杂交可能会改变正常的配子发生和受精途径：罕见的“无性繁殖”的出现。这类脊椎动物可以解决有关性行为、配子发生和受精的根本性问题。然而，从有性行为转变为“无性行为”的原因和机制并没有得到很好的研究。在四种二倍体和三倍体“无性”无尾两栖动物和鱼类复合体(眼镜蛇和台湾无尾无尾两种)中，我们比较了不同的“无性”模式、触发因素和关键途径。利用细胞遗传学、细胞生物学、基因组学等综合方法，我们将阐明：1)减数分裂前基因组消除或内复制或减数分裂失败引起的配子发生的改变；2)受精后精子的去除；3)双性亲本和“无性”杂交种中性染色体的同一性，包括4)启动“无性”的潜在作用。

Sexual reproduction, prevailing in most eukaryotes, involves meiosis with recombination, reduced gametes, fertilization, karyogamy, and development of a new organism. Breaking this rule, hybridization in vertebrates may alter the canonical gametogenic and fertilization pathways: the emergence of rare "asexuality". Such vertebrates allow to address fundamental questions about the persistence of sexuality, gametogenesis and fertilization. However, causes and mechanisms of switches from sexuality to "asexuality" are poorly examined. In four diploid and triploid "asexual" anuran (Pelophylax) and fish complexes (two in Cobitis; Poecilia formosa), we compare different "asexual" modes, triggers and key pathways. Using integrative approaches (cytogenetics, cell biology, genomics), we will elucidate: 1) modifications of gametogenesis by premeiotic genome elimination or endoreplication, or failure of meiosis; 2) sperm elimination after fertilization, 3) identity of sex chromosomes in parental bisexual species and "asexual" hybrids including 4) a potential role to initiate of "asexuality".